Polishing wheel



Sept. 21, 1965 P. E. SCHAFFNER 3,206,894

POLISHING WHEEL Filed April 29, 1959 ummmmumm unmmmmmm 9 United States Patent O 3,206,894 POLISHING WHEEL Paul E. Schaffner, Wexford, Pa., assignor to Schaffner Manufacturing Company, Inc., Emsworth, Pa., a corporation of Pennsylvania Filed Apr. 29, 1959, Ser. No. 809,647. 6 Claims. (Cl. 51-336) This invention relates to the polishing or bufling art and has particular relationship to polishing wheels. The expression polishing wheel is used in this application in its general sense and is meant to include within its scope buing and finishing as well as polishing wheels.

Application Serial No. 193,446, filed May 9, 1962, is a division of this application. This invention in its specific aspects concerns itself with polishing wheels composed of a plurality of flaps of abrasive material. Usually such flaps are abrasive on one side and smooth on the other. Such wheels are in the form of an annulus usually (but not necessarily) with the abrasive surface of each ap contiguous to a smooth surface of the adjacent ap and with the radially inner ends of the flaps bonded together by an adhesive between the surfaces of the aps.

The making of such wheels, in accordance with the teachings of the prior art, has disadvantages. The bonding of the inner surfaces presents a serious problem.

In accordance with the teachings of the prior art, the annulus is provided with flanges, one of which has an opening in the center and the adhesive is injected through this opening while the annulus is rotated at a substantial speed about a horizontal axis. The adhesive is injected between the flaps by centrifugal force. The injection of the adhesive presents difficulties. In addition the hubs of wheels of this type have been found to be fragile and to crack during shipment.

There are disadvantages in the prior art wheels themselves. In use the wheels are rotated at a high speed, the abrasive surfaces of the flaps successively engaging the work. Excessive heat develops during such use and the aps are charred materially shortening the life of the wheels. In addition, the ends of the llaps fray sub- Stantially.

It is then a specific object of this invention to provide polishing Wheels composed of abrasive flaps which shall not have the disadvantages of prior art wheels.

More specifically stated, it is an object of this invention to provide low-cost, readily usable wheels of abrasive flaps, the hubs of which shall be resistant to fracture.

Still another specific object of this invention is to provide a low-cost polishing wheel in the form of an annulus of flaps and particularly of abrasive flaps which shall have a fracture-resistant hub.

A still further object of this invention is to provide a polishing wheel in the form of an annulus of flaps and particularly of abrasive aps in the use of which the ends lof the flaps shall not fray and shall not deteriorate from excessive heating.

This invention, in one of its specific aspects, arises from the realization that in the practice of the prior art method tht `distribution of adhesive over the surface of the radially inner edges of the aps of the annulus is not uniform because of the manner in which the annulus is rotated to inject the adhesive between these surfaces. This disadvantage and the difficulties in applying the adhesive are both overcome in accordance with this invention by conning the liquid adhesive in a horizontal pool within the annulus and then rotating the annulus and adhesive about a vertical axis. During this rotation the adhesive is injected uniformly between the flaps. It has been4 found that highly effective penetration can be produced even where the flaps are tightly packed. The speed Patented Sept. 2l, 1965 of rotation and the viscosity of the adhesive are correlated so that the adhesive is injected only over a suitable distance from the inner periphery of the annulus towards the outer periphery of the annulus and not beyond this distance. After the adhesive is injected it is cured, and it has been found that a wheel with a strong fractureresistant annulus results.

The annulus and adhesive may be rotated together. But in accordance with an important specific aspect of this invention the annulus and adhesive are rotated separately at different speeds. The relative rotation of the annulus and adhesive assures uniform distribution of the adhesive over the radially inner ends of the annulus and the uniform penetration of the adhesive between the surfaces contiguous to these ends.

The fracture-resistance is further increased by mounting the flaps on a resilient ring which serves not only to facilitate the formation of the flaps into an annulus but also in strengthening the hub. In accordance with one aspect of this invention the ring may be solid. During the formation of the annulus the ring is inserted in the flaps through slits extending from the radially inner ends engaging an opening at the ends of the slits. When the aps extend around substantially the whole ring, the adjacent llaps at one point of the ring are separated and clamped under substantial pressure and additional flaps are inserted between the separated flaps. When the pressure is relieved the flaps are thus tightly packed on the ring.

The ring may also be split with the ends interlocked by notches or the like. In this case the aps need not have slits but must have holes near the edges which are to form the radially inner periphery of the annulus. In this case the ring is separated at the split and the flaps in bundles with the holes aligned are slipped over the ends of the ring. When the aps are tightly packed the ring is permitted to spring back so that its ends interlock.

When the `annulus is assembled flanges are placed on each side of hub to keep the annulus aligned. Adhesive is then applied. The adhesive should penetrate beyond the ring so that the ring serves as reinforcement for the adhesive analogously to the metal in reinforced concrete. The ring should preferably be positioned in the region where the hub is tensioned when stress is applied to it.

The charring of the flaps during use is prevented by cooling the wheel. For this purpose the wheel is provided with cooling slots extending radially inwardy. Each flap has at least one slot extending inwardly from the radially inner end. When the ilaps are formed into an annulus the slots are aligned to form a slot having the configuration of a disc. The slots extend beyond the parts of the surfaces where the adhesive penetrates.

When the annulus is being prepared for rotation to inject the adhesive the slot is masked by tape which may be removed before or after curing. The slot provides a passageway for cooling air.

To suppress the fraying, the flaps are cut out from the matrix cloth on a bias.

The novel features considered characteristic of this invention are disclosed generally above. The invention itself both as to its organization and as to its method of operation, together with additional objects and advantages thereof, will be understood from the following description of specific embodiments taken in connection with the accompanying drawings, in which:

FIGURE 1 is a view in side elevation of a flap used in the practice of this invention;

FIG. la is a view in side elevation showing how the flaps shown in FIG. 1 are mounted in a solid ring to form an annulus;

FIG. 2 is a view in side elevation showing how the 3 flaps shown in FIG. 1 (or like aps without slits) are mounted on a split ring to form an annulus;

FIG. 3 is a fragmental view showing how the ends of the ring interlock;

FIG. 4 is a view in longitudinal section showing apparatus of one type for practicing this invention;

FIG. 5 is a view in longitudinal section showing apparatus of another type for practicing this invention;

FIG. 6 is a view in longitudinal section showing apparatus ofa third type for practicing this invention;

FIG. 7 is a view in perspective showing a polishing wheel in accordance with this invention;

FIG. 8 is a View in longitudinal section showing the manner in which a polishing wheel in accordance with this invention is used;

FIG. 9 is a view in perspective showing a polishing wheel in accordance with a modification of this invention; and

FIG. 10 is a view in section showing a polishing wheel in accordance with another aspect of this invention.

The flap 11 in accordance with this invention is of generally rectangular form with a stern 13 extending from one side of the rectangle. The stem has notches 15 and 17 and 19 and 21 which are symmetrically disposed with reference to the longitudinal axis of the stem. The stem 13 also has a slit 23 (FIG. 6) which terminates in a hole 25 and a pair of slots 27. The slots 27 extend an appreciably greater distance from the end of the stem 13 than the hole 25. The flap 11 is preferably coated with an abrasive on one side and is smooth on the opposite side.

In the practice of this invention a large number of flaps 11 are formed into an annulus in which the aps are tightly packed. The annulus is produced by stringing the aps 11 on a solid ring 30. Bundles of the flaps 11 are assembled with the slits 23 and the holes 25 aligned and are mounted on the ring 30 by slipping the ring 30' through the slits 23 until the ring 30 engages the holes 25. When the ring 30 is substantially lled, adjacent flaps 32 and 34 at one point are pressed back and clamped, and additional iiaps 11 are slipped onto the ring 30. Flaps 32 and 34 are then released and a tightly packed annulus is formed.

The flaps 11 may also be strung onto a resilient split ring 31. In this case the slits 23 may be omitted. The ends 33 and 35 of the ring 31 are provided with mating notches 37 and 39 which overlap so that in the closed position the ring 31 is locked by the engagement of the notches 37 and 39.

In forming the annulus the ring 31 is opened and the flaps 11 are mounted on the ring by threading the holes 25 in the flaps over the split ends of the ring. A plurality or bundle of flaps 11 may be strung onto the ring during each Stringing operation. Each bundle should be assembled so that the slits 23 are coextensive and the slits of the bundle should Ibe passed together over the ring 31.

When a sufficient number of aps 11 have been strung on the ring 31 to form a tightly packed annulus the ends 31 are released and permitted to snap into engagement. The annulus 40 which is thus formed has a hub supported on ring 31, circular grooves formed by the notches 15, 17, 19 and 21 and circular slots formed by the slots 27.

The rings 30 and 31 may be composed of metal. While mild steel or aluminum may be used, spring steel is preferred in certain situations.

The annulus -is now provided with a solidified hub. For this purpose the stems 13 are secured together by an adhesive. The adhesive may be formed by combining a resin such as Hysol 2030 or Bakelite ERL-2774 with a hardener such as diethylene triamine, Bakelite ZZLD-08l4 or combinations of the diethylene triamine and BakeliteZZLD-08l4. The adhesive consists of 100 parts by weight of resin and 10 to 40` parts by weight of hardener. The hardener may have any composition between triamine and 0 of '0814 and O` of triamine and 100% of 0814. The adhesive so formed is a liquid and is injected between the surfaces of the stems 13 by centrifugal force. The higher the triamine the lower the viscosity of the adhesive.

j For this purpose, a receptacle 41 (FIG. 4) mounted on a turntable 42 to rotate about a vertical axis is provided. The receptacle 41 includes a cylindrical wall 43 and the space within which is closed by upper and lower plates 45 and 47. The lower part 49 of the wall 43 is solid and the Aupper partv 51 is perforated. The lower plate 47 may be secured to the lower part 49 of the wall 43, for example, by welding and has a projection 53. An annular trough is thus formed between the projection 53 and the part 49 in which the liquid adhesive 55 is disposed. The upper plate 45 may be flat. This plate may be removably mounted on the wall 43. Each of the plates 45 and 47 extends beyond the wall 43 and the extending portions are provided with annular projections 61, 63, 65 and 67 adapted to engage the grooves 15, 17,19, 21 of the annulus 40.

In the practice of this invention the plate 45 is removed from the wall 43 and the adhesive 55 is poured into the trough between part 45 and projection 53. The circular slots 27 in the annulus 40 are then closed by strips of adhesive tape 71 extending around the radially inner wall of the annulus 40 at the slots 27. The annulus 40 is then mounted encircling the wall 43 with its grooves 17 and 21 engaging the projections 65 and 67. To facilitate removal of the annulus after treatment, polyethylene sheet or silicone parting agent (not shown) may Abe interposed between the -grooves 17 and 21 and the projections 65 and 67. The top 45 is then mounted on the wall 43 with the projections 61 and 63 engaging the grooves 15 and 19. Polyethylene sheetv or a conventional mold release or parting agent (not shown) may also be interposed in this case between the projections 61 and 63 and the grooves 15 and 19. The annulus 40 should be held tightly between the plates 45 and 47.

The assembly 41-40 is then mountedv on the turntable 42 and rotated. The rotation causes the adhesive 55 to rise along the wall 43 and be projected through the openings 73. The adhesive impinges on the radially inner periphery 75 of the annulus 40 and because the rotation of the annulus 40 is injected between the surfaces of the stems 13 of the aps 11. Su'icient adhesive ilows down the wall 75 to provide for coating of the portions of the surfaces of the stem 13 opposite the part 49 of the wall 43. The speed of rotation should be so coordinated with the viscosity of the adhesive that the adhesive is injected only to the region justbeyond the ring 31 (FIG. 8) and not beyond the inner ends of the slots 27. The following table shows relationships between viscosity, speed and time of injection which have proven satisfactory for the above-described adhesives The viscosity was set in each case by adjusting the prol portions of the hardeners diethylene triamine and Bake lite ZZLD-0814.

Viscosityin Centipoise Rotational Speed,

Time of Treatments, r.p.m. Minutes ly distributed over the hub. The ring 31 serves as reinforcement. The slots 27 which are free of adhesive throughout and communicate with the separable parts of the llaps 11 serve to ventilate the wheel in use.

When the wheel 81 is to be used, it is provided with end plates 91 and 93 having projections 95 which engage the grooves 15, 17, 19, 21. The plates 91 and 93 have central openings through which a shaft 97 passes. The shaft 97 is threaded and is held in firm engagement with the plates 91 and 93 by nuts 99. The plates 91 and 93 have perforations 101 `in their faces.

In use the shaft 97 is rotated rotating the wheel 81. The outer periphery of the wheel 81 is in polishing engagement with the Work while the wheel is rotated. The heat developed by the polishing is to a large extent carried away by the cooling air owing through the holes 101, the slots 27 and between the unjoined parts of the flaps 11.

To improve the distribution of the adhesive the annulus 40 is rotated at a different speed than the adhesive. This is accomplished with apparatus as shown in FIG. 5 which includes a cup-shaped receptacle 111 having a solid base 113 and a wall 115 which is solid in the lower part and perforated in the upper part. A vertical shaft 117 extends from the center of the base 113. The adhesive 119 is disposed in the lower part of the receptacle 111. The apparatus also includes lower and upper plates 121 and 123 each having annular projecti-ons 125 and 127 adapted to engage the grooves 15, 17, 19 and 21 in the annulus 40. A hollow shaft 131 extends from the lower plate 121 and this plate is also provided with an opening coaxial with the shaft 131 adapted to accommodate the shaft 117.

When this apparatus is to be used the plate 121 is mounted on a bearing plate 133 with a bearing ring 135 extending from plate 121 en-gaging bearings 137 in plate 133. The receptacle 111 with the adhesive 119 in the base is mounted on plate 121 with the shaft 117 extending through plate 121 and shaft 131. The shaft 117 extends below shaft 131. The annulus 40 (with slots 27 taped) is then mounted on plate 121 (preferably with polyethylene sheet or a suitable mold release agent interposed between 17, 21 and 125). The upper plate 123 is then mounted on the annulus 40 and bolted to the lower plate 121 by bolts 141 passing between the receptacle 111 and the annulus 40. The shafts 117 and 131 may then be provided with driving pulleys 143 and 145 and the annulus assembly 40-121-123 and receptacle 111 rotated at different speeds. The direction of rotation may be the same or opposite The speed of the receptacle is so related to the viscosity of the adhesive 119 that the adhesive is projected on the radially inner surface 75 of the annulus. The speed of the annulus is so related to the viscosity of the adhesive that the adhesive is injected between the surfaces of the stem 13 as described above. annulus is cured and a polishing wheel 81 as described above is produced.

The adhesive may also be injected into the annulus 40 under pressure. For this purpose the apparatus shown in FIG. 6 is provided. This apparatus includes a flanges lstub 161 and cooperative plate 163. The flange 165 of the stub 161 includes projections 167 adapted -to engage the grooves 19 and 21. The pla-te 163 has like projections 169. The annulus 40 is compressed between the flange 165 and 163 by bolting the plate 163 to the stub 161. O-rings 171 and 173 are compressed between the grooves 15 and 19 and the projections 167 and 169. Adhesive is then injected under pressure through openings 175 in the plate 163. The pressure causes the adhesive to penetrate between the surfaces of the stems 13. After this treatment the annulus 40 is cured.

A modified wheel 191 in accordance With this invention is shown in FIG. 9. This Wheel is made up of flaps 193 which do not have slots 27. The flaps 193 may be formed into an annulus and treated in the same manner as After this ltreatment the' the flaps 11. A wheel 191 having a solid hub is thus formed. After the wheel is formed holes 195 are drilled through the hub. This object may be accomplished by separating the unjoined ends of the flaps 193 at selected regions and drilling through the hub at these points. The holes 195 serve for ventilation purposes.

In the wheel shown in FIG. 10 the flaps 11 and spacers 301 alternate. The spacers 301 may be made of wood or cardboard. The wheel shown in FIG. 10 may be joined at the radially inner ends in the same way as the other polishing wheels.

While preferred embodiments of this invention have been .disclosed herein, many modifications thereof are feasible. This invention then is not to be restricted except insofar as is necessitated by the prior art.

I claim as my invention:

1. An abrasive wheel comprising an annulus of abrasive llaps, each of said flaps -being substantially planar and the plane of each flap diverging from the axis of said annulus and the extension of each plane including said axis, the surfaces of adjacent aps being bonded together along a predetermined length radially from their inner ends, each said ap including at least one radial slot extending radially from the inner boundary of said ap a distance greater than said length, said slots of said flaps being superimposed in said annulus so as to constitute at least one Ventilating slot for said wheel.

2. A polishing wheel comprising an annulus of flaps, said aps extending continuously around said annulus and each of said flaps being substantially planar and the plane of each ap diverging from the axis of said annulus and the extension of each plane including said axis, the radially inner surfaces of said aps being bonded together by an adhesive along a predetermined length radially from the inner ends of said iiaps, said annulus including at least one Ventilating opening extending radially from the radially inner boundary of said annulus a distance greater than said length.

3. An abrasive wheel comprising an annulus of abrasive aps, said flaps extending continuously around said annulus and each of said flaps being substantially planar and the plane of each flap diverging from the axis of said annulus and the extension of each plane including said axis, each of said flaps also being cut out on a bias, the surfaces of adjacent flaps being bonded together along a predetermined length radially from their inner ends, said annulus including at least one Ventilating opening extending radially from the inner boundary of said annulus a greater distance than said length.

4. An abrasive wheel comprising an annulus of abrasive flaps, each of said aps being substantially planar and the plane of each flap diverging from the axis of said annulus and the extension of each plane including said axis, the surfaces of adjacent flaps being bonded together along a predetermined length radially from their inner ends, each said flap including at least one radial slot extending radially from the inner `boundary of said flaps a distance greater than said length, at least some of said slots of said aps being superimposed in said annulus so as to constitute at least one Ventilating slot for said wheel,

5. A polishing wheel comprising an annulus of flaps mounted on a solid ring, the radially inner surfaces of said aps being bonded together by an adhesive along a predetermined length radially from the inner ends of said aps, said length being substantially smaller than the length of said flaps, said adhesive extending radially outwardly and inwardly on both sides of said ring.

6. A polishing wheel comprising an annulus of flaps mounted on a solid reinforcing ring, the radially inner surfaces of said flaps being bonded together by an adhesive along a predetermined length radially from the inner ends of said flaps to form a hub, said length being substantially smaller than the length of said flaps, said adhesive extending radially inwardly and outwardly on both sides of said ring and being positioned in the region where USC.

said hub is tensioned when stress is applied tg said hub in References Cited by the Examiner UNITED STATES PATENTS Leggett 51-193.5 l Pileghar 51-193 Painter 51--193 Zimmerman 51-193 Hall 51-193 Davis 51-190 Sayers 51-'193 Bahr 51-193 Schloss 51-193 McAleer .v 51-'193 Leggett- 51-193.5 Leggett 51-193.5 Churchill 51-193 Block 51-293 Block 51-293 Block 51-193.5 Thomson 51-193.5 Bernslein 51-193.5 Miller et al 51-1935 ROBERT C. RIORDON, Primary Examiner. FRANK E. BAILEY, FRANK H. BRONAUGH,

Examiners. 

2. A POLISHING WHEEL COMPRISING AN ANNULUS OF FLAPS, SAID FLAPS EXTENDING CONTINUOUSLY AROUND SAID ANNULUS AND EACH OF SAID FLAPS BEING SUBSTANTIALLY PLANAR AND THE PLANE OF EACH FLAP DIVERGING FROM THE AXIS OF SAID ANNULUS AND THE EXTENSION OF EACH PLANE INCLUDING SAID AXIS, THE RADIALLY INNER SURFACES OF SAID FLAPS BEING BONDED TOGETHER BY AN ADHESIVE ALONG A PREDETERMINED LENGTH RADIALLY FROM THE INNER ENDS OF SAID FLAPS, SAID ANNULUS INCLUDING AT LEAST ONE VENTILATING OPENING EXTENDING RADIALLY FORM THE RADIALLY INNER BOUNDARY OF SAID ANNULUS A DISTANCE GREATER THAN SAID LENGTH. 